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Provably the most reasonable way to build a vehicle like this, will be using a fibre glass/carbon body and reinforce it with internal ribs or a metallic chassis underneath, or may be both.
True... and that's a BMW i3. It's practical as a home build, if you use a simple frame as a base with a composite (or even just thermoplastic) body on top.

Even if going throw the 3D printing way, to use just hobby printers is not the right or optimal way. I am aware of that as well.
The most reasonable way of 3D print a car like this, it is probably to use a huge 3D printer and print it all at once or may be in some big parts.
Speaking of size... with actual hobby printers (not some product that isn't even available yet) what are your maximum part dimensions? Some hobbyists have built quite large 3D printers, but those are not "standard hobby printers". It might make sense to open up the constraints a bit, and consider using a larger printer that can be built from a readily available kit.
 

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The constraint here is "3d printed".
It's actually this, which is substantially different and far more restrictive:
...to be made with standard hobby printers and easy to find/work PLA, and/or maybe PETG plastic. Some small parts printed with Nylon...
Can it be done, more whimsical than reality. Some of you are missing that.
I'm not missing that. I'm just looking for some reality in the description - 3D printed body (not 3D printed car) - and in expectations of what the material can reasonably do, particularly when building a large object from small pieces.
 

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Discussion Starter #23
Speaking of size... with actual hobby printers (not some product that isn't even available yet) what are your maximum part dimensions? Some hobbyists have built quite large 3D printers, but those are not "standard hobby printers". It might make sense to open up the constraints a bit, and consider using a larger printer that can be built from a readily available kit.
I have already cut the parts to fit printers with a build volume of 220x220x220mm that is actually quite standard for hobby printers. The one I own now is 220x220x230mm
The actual tendency in hobby printers is going to bigger build volumes 300x300x300mm and up.
If I am able to gather enough economic resources I plan to buy one printer with that bigger sizes and then cut the parts to fit in that larger printers.
And obviously use that bigger printer for the job.

I think by tomorrow I will have ready some sample parts files to publish so you will be able to see how its made.

 

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Discussion Starter #24 (Edited)
As commented I just created today a project in Prusa printers and Thingiverse because I will be releasing the Open Source in a few days (maybe weeks…) and needed the links for the documentation.
And because in some forums people wanted to see more and see how the parts are, and if they can print them.
So I just uploaded in the projects a couple samples pieces of the body, anyone can print them with the printing suggestions and profiles detailed and check if they like the idea.
Please post your prints and please give some feedback.

Link to PrusaPrinters: https://www.prusaprinters.org/prints/46 ... ellybean3d
Link to Thingiverse: 3D PRINTED DIY ELECTRIC CAR, The Jellybean3D by GonzaloChomon
Any suggestion and help is welcome. Feel free to comment.
120848
 

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I assume that the colour patchwork is just to show the shape. Do you have a version yet that shows how the body is divided into 300 mm x 300 mm x 300 mm parts?
 

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Discussion Starter #26
I assume that the colour patchwork is just to show the shape. Do you have a version yet that shows how the body is divided into 300 mm x 300 mm x 300 mm parts?
What you can see on that image are the different parts. Now cut to fit 220x220x220mm printers (I own one about that size)
If I gather enough resources, I will get a larger one (300x300x300mm+) and will perform the cuts for that printers size.
The colour patchwork is made in order to see better the different parts.
A sample part image:
120873
 

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I would add some features like a key way or slot to allow for better mechanical attachment to each other, also what material are you looking at for bonding the parts together?
A good structural adhesive like 3M DP490 works very well on PLA
 

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What you can see on that image are the different parts. Now cut to fit 220x220x220mm printers (I own one about that size)
Okay, thanks. The patchwork just looked a little random to me to be a plan for parts... for instance, wouldn't you make the headlight housing as one part, and the concave area in front of it as another part, to avoid the most obvious seams? Wouldn't you overlap rib sections over body panel sections, rather than having their joints line up?

I would add some features like a key way or slot to allow for better mechanical attachment to each other...
Absolutely! Just ending parts with butt joints would be a structural nightmare, especially in those ribs. They need to mechanically interlock or at least have joints which provide suitable adhesive bonding surfaces. To illustrate this, take a plastic model of a vehicle, saw it into a checkerboard of pieces, and see if you can glue it back together into anything other than a fragile mess.
 

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Discussion Starter #29
I would add some features like a key way or slot to allow for better mechanical attachment to each other
I will love to do so, but I have not found a way to automate that kind of features in the CAD software. Doing them by hand is almost imposible (over 2000 features) and if it is not automated (like a pattern or so) the CAD files provably colapse with so many operations.

what material are you looking at for bonding the parts together?
The final construction material has not been chosen yet. So final bonding method has not beed decided either..
But I have done some previous tests on PLA with different glues including different structural epoxies and the one that works best is Cyanoacrylate, even the cheapest one bonds better that the best epoxy.
But cyanoacrylate does not produce strong permanent bondings on things that are going to be exposed to moisture, sunlight and temperature differences.
So I will provably will use chemical welding instead of glueing, but I still didn't have time to test this method.

Okay, thanks. The patchwork just looked a little random to me to be a plan for parts... for instance, wouldn't you make the headlight housing as one part, and the concave area in front of it as another part, to avoid the most obvious seams?
It is not easy to perform the cuts as many things have to be taking in account:
  • Printer size, so the parts fit in the printing volume.
  • Printing orientation, in order to get the most strength in the directions that are more need in the part and make them coincident with the XY printing plane.
  • Cut in the appropriate orientations and locations in order to avoid the use of supports when printing.
  • Avoid or enforce the cuts in determinate areas in order to strengthen or not weaken them.
That is why it looks a bit random, but actually it is not random at all.

Wouldn't you overlap rib sections over body panel sections, rather than having their joints line up?
Sorry, do not understand this question.
 

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If the 3D printing software can't handle making the pieces so they can be joined properly, I don't see much point in using it. You might as well carve the shape in foam and lay fiberglass on it, as has been done for decades, and have a lighter and stronger shell... probably with less manual effort than piecing this together. I understand that the idea is a 3D printing challenge, but doesn't that mean you should solve the joint problem as part of that challenge, rather than just ignoring it?

If you look at a brick wall, they are never (unless they are purely decorative) built with all of the vertical joints lined up, the way you have lined up panel joints and rib joints. Bricks in each row overlap the joints in the rows above and below, so the wall isn't so likely to just fold at a vertical joint. These patterns of bricks are called bonds; while you're not working with masonry, the same idea of avoiding problems at joints applies.

If you can find the right adhesive, you might be able to make those patchwork ribs actually useful by printing them as two half-thickness pieces, bonded together, with staggered joints. Far more effort and material than just putting a couple of bends in an aluminum strip with a brake to make a stronger rib, but still 3D printed...
 

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Discussion Starter #31
I made a printable 1/10 scale model of the Jellybean3D, let me know what you think.
You can download the file parts for printing from: PrusaPrinters
Check this short video for printing, assembly instructions and other details:

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That forthcoming printer I mentioned is now sitting at $1M worth sold, at about $600 a pop. People have printed next-to-useless, lol, 20 foot I-beams on the prototypes. Unlike many Kickstarters, this is being used as a sales channel (Kickstarter used to be strict about funding creativity, then they basically turned themselves into whores, IMO) by one of the largest printer makers in China. The carbon fiber filament makes the print stiffer, but does next to nothing for strength. You can pause the printer and add rods,hardpoints, nuts, etc, to embed them into the plastic.

Severely compromised way to do it, more challenging than doing it the "right" way...which seeds innovation.
 

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^^ What you could do is "Crowd print" the pieces.

This was done for a hobbyist get together where everyone pitched in with printing a piece of a very large project a few years ago and got to be part of it. I don't recall the details as that part of my brain is still in "longhauler" Covid fog. Might have been Adam Savage for an Ironman suit, maybe.

As far as joining, good old dovetails works, as would using rods on the inside threaded through surface "eyelets" in the part
 

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He can probably attach the eyelets while in assembly. Think piano hinge.

There are other tricks you can do on the solids with Booleans while it's in assembly...maybe.
 

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Plates wouldn't reinforce it, though I suppose you could rivet half-thickness plates together for double the print-time fun and to get your repurposed steam-boiler look.
 
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